Xiaomi in-Ear Headphones Pro

Dual sound unit, more musical detail, 20 step to build metal sound chamber.
Hybrid technology. Dynamic and balanced armature drivers.
Dynamic driver technology is implemented into a variety of products including loudspeakers, headphones, and in-ear monitors. Unlike balanced armature designs, dynamic drivers are designed to cover the entire frequency range. While this often results in less detail from a scientific point of view, many people find dynamic drivers to be more natural sounding due to the absence of a crossover sending specific frequency bands to different drivers.
Balanced armature drivers are primarily used in hearing aids, but they also see extensive use in modern in-ear monitors. Most balanced armature drivers are tuned to sound good in a specific frequency range, and this is why many in-ear monitors contain multiple drivers. A crossover splits the sound signal into multiple frequency bands, and sends different frequency bands to each driver.